Display device for a wristwatch

ABSTRACT

The invention relates to a display device for a wristwatch comprising a luminescent surface for illuminating the background of a display element consisting of one or more alphanumeric characters. The display device comprises a window in an opaque watch face in which these characters can be displayed. The luminescent surface covers at least one partial area of a supporting surface situated behind said window. The alphanumeric characters of the display element have an opaque material and are located between the watch face and the luminescent surface.

The invention relates to a display device for a wristwatch having aluminescent surface for the background illumination of a displayelement.

It is known from the prior art for digital displays for dates, days ofthe week and/or chronometer functions to be provided with numbers, inwhich case an analog movement mechanism simultaneously displays hours,minutes and seconds using hands.

Such timepieces have the advantage that they can be configured purelymechanically and thus do not require any energy source such as a batteryand/or a solar cell in order to function. The problem with these analogtimepieces, then, is to render the display visible in the dark. For thispurpose, it is possible to provide a battery or rechargeable storagebattery, by means of which a luminous unit is supplied with energy. U.S.Pat. No. 6,208,591 utilizes a luminescent layer which is arranged in andbeneath the then transparent face. This luminescent layer illuminatesthe hands of the timepiece from behind. However, it is thus not possibleto render additional digital information of the timepiece readable inthe dark.

It was also known to apply luminescent materials to the hands in orderfor the latter to be luminous in the dark. The application of thesematerials to numbers which indicate the digital time units, however, isassociated with two significant problems. On the one hand, theapplication of these materials results in these digital time displaysbecoming considerably thicker. Furthermore, such displays only appear ina window during the corresponding time unit and are otherwise covered bythe face, with the result that they are not recharged to a sufficientextent.

There is no question of using radioactive products for sales oftimepieces in the civilian sector.

Wristwatches, finally, are often provided exclusively with a digitaldisplay of time units. These watches are usually with an LCD display.Such watches require a power source.

Taking this prior art as the departure point, the object of theinvention is to configure a display device of the type mentioned in theintroduction such that the digital time display is also visible in thedark.

This object is achieved according to the invention, for a display devicefor a wristwatch of the type mentioned in the introduction, by thefeatures of claim 1.

Since it is exclusively the region behind the window in the face whichis coated with the luminescent material, it can be ensured that thisregion is constantly recharged when the watch is worn, provided thewatch is not covered by clothing. The numbers which appear in the windoweither are introduced in a transparent disk or consist essentially of apunched-out material, the parts of which are connected to one anothermerely via thin connecting crosspieces. This has the advantage that itis only in the region of this window that account has to be taken of theconsiderable thickness of the luminescent material, but the numberdisks, which bear the digital time-display units, may be of very thinconfiguration, in the customary manner.

Further advantageous embodiments are characterized in the subclaims.

The invention will now be described by way of example using exemplaryembodiments and with reference to the attached drawings, in which:

FIG. 1 shows a schematic plan view of a wristwatch with a digital datefunction according to a first exemplary embodiment of the invention,

FIG. 2 shows a schematic plan view of a wristwatch with a digitalchronometer function according to a second exemplary embodiment of theinvention,

FIG. 3 shows an exploded view with a schematic illustration of theregion around the window of the first exemplary embodiment according toFIG. 1, and

FIG. 4 shows an exploded view with a schematic illustration of theregion around the window of the second exemplary embodiment according toFIG. 2.

FIG. 1 shows a plan view of a wristwatch with a face 1, an hour hand 2,a minute hand 3 and a second hand 4. Also provided are two windows 5 and15, in which it is possible to see the current date, in this case thenumber 15 for the fifteenth day of the month, and, in this case, theletters “Sat” for the current day of the week (Sat for Saturday). Thedisplay elements are designated in general terms by 42. It is, ofcourse, also possible to provide just one window 5. The configurationaccording to the invention of the region of the window or windows 5, 15is illustrated in the detail-form drawing of FIG. 3.

FIG. 2 shows a different wristwatch, this time configured as achronometer. The same features are indicated by the same designations inall the figures. This watch according to FIG. 2 likewise has the hourhand 2, the minute hand 3 and the second hand 4. A further coaxialsecond hand 14 is provided for the chronometer function. The stoppedminutes can be seen in the window 25 (in this case eight minutes) andthe stopped and elapsed time in hours (in this case one hour) can beseen in the adjacent window 35.

The hands 2, 3 and 4 and also 14 in the exemplary embodiments accordingto FIGS. 1 and 2 are each provided with conventional luminescentcoatings 8, with the result that the hands can also be read in the dark.The windows 5, 15 and 25, 35 are configured in accordance with theinvention in order that the alphanumeric characters there can also beread in the dark, this being described in more detail by way of twoexemplary embodiments in conjunction with FIGS. 3 and 4.

FIG. 3 shows a schematic exploded view of a first exemplary embodimentfor displaying the number “8” in the window 5. The configuration for thewindows 15, 25 and 35 may be identical in each case. The window 5 is anopening, in this case of square form, in the face 1. At least one disk21, preferably rotating about the hand axis, is arranged beneath theface 1. An essentially square section of the disk is illustrated here,this section having light acting on it through the surface area of thewindow 5. It is possible to provide one disk 21 per display unit, i.e.two disks for the day of the week and date, and three disks for hours,10s of minutes and minutes for a chronometer function.

The disk 21 which is illustrated here by way of example comprises aregion 23 of transparent material which has arranged in its interior 25or on its surface at the top 24 or bottom 26, preferably at the top 24,an opaque display element, in this case the number “8”, which isdesignated 22. Arranged beneath this rotating disk 21, opposite thewindow 5, is a disk 19 which is fixed in relation to the housing of thewatch and, in its central region, is provided with luminescent material,designated 29 here. The surface coated by the luminescent material 29 isadvantageously somewhat larger than the opening of the window 5, withthe result that even slanting incident light through the window 5, thislight passing through the disk 21, illuminates border regions of theluminescent material and thus also charges the same.

The disk 21 is advantageously highly transparent and has a slightlydiffusing action on its underside 26, with the result that, irrespectiveof the region covered by the display element 22, those sub-regions ofthe surface 29 which are located directly beneath the display element 22also receive light. It is thus the case with each type of display, i.e.with each date and/or each day of the week and/or the chronometernumbers, that most of the surface 29 in each case is illuminated, withthe result that, when it is light, the (dark) display element 22 can beread against the light background and, in the dark, it is visible as anegative in relation to the light-emitting element 29.

FIG. 4 shows another embodiment of the invention, the window 5 in theface 9 and the luminescent surface 29 in the region 19 being the same.The difference in relation to FIG. 3 relates to the type of displayelements, in this case designated 32. The display element 32, in thiscase-the number “0”, is connected via small crosspieces 33 to a carrierstructure 34 which, as it were, replaces the disk 21, which for eachdisplay of an alphanumeric character, in this case of a number, islocated outside the window 5. The carrier structure may be connected tothe inner region of the carrier via a radial connecting crosspiece 35.All the crosspieces 33, 34 and the character 32 are of very thinconfiguration and, for reasons of simplicity, are illustrated intwo-dimensional form without any thickness.

It is thus possible for the light passing in through the window 5 to acton the luminescent surface 29 without obstruction, with the exception ofthe region covered by the display element 32. All the crosspieces 33and/or the carrier structure 34 may be of transparent configuration andonly the display element 32 is opaque, or is made of the sametransparent material as the crosspieces 33 but coated with an opaquematerial.

Both the cases mentioned in FIGS. 3 and 4 have the advantage that thewristwatch provided with this system remains readable in the dark for along period of time even after the luminescent materials on the surface29 have been recharged for only a short period, this being the case bothfor the traditional hour, minute and second display elements and for theadditional chronometer function and/or date/day of the week function.

1-7. (cancelled)
 8. A display device for a wristwatch having aluminescent surface for the background illumination of a displayelement, wherein the display element comprises at least one alphanumericcharacter displayed in a window of an opaque face, wherein theluminescent surface covers at least one sub-region of a carrier surfacewhich is arranged behind said window, wherein the at least onealphanumeric character of the display element includes an opaquematerial, and wherein the at least one alphanumeric character of thedisplay element is arranged between the face and said luminescentsurface.
 9. The display device as claimed in claim 8, wherein the atleast one opaque alphanumeric character of the display element isarranged within a moveable transparent disk, wherein the moveabletransparent disk is arranged parallel between the face and saidluminescent surface.
 10. The display device as claimed in claim 8,wherein the at least one opaque alphanumeric character of the displayelement is fastened on or beneath a moveable transparent disk, whereinthe moveable transparent disk is arranged parallel between the face andsaid luminescent surface.
 11. The display device as claimed in claim 9,wherein the transparent disk is configured on the underside so thatlight passing through it is diffused.
 12. The display device as claimedin claim 10, wherein the transparent disk is configured on the undersideso that light passing through it is diffused.
 13. The display device asclaimed in claim 8, wherein the at least one alphanumeric character ofthe display element is connected via crosspieces to a supportingstructure which defines a plane, wherein said plane is arranged parallelbetween the face and said luminescent surface.
 14. The display device asclaimed in claim 13, wherein the at least one alphanumeric character ofthe display element and the crosspieces consist of a transparentmaterial, and wherein the at least one alphanumeric character is coveredwith an opaque material on one of a top side and an underside of the atleast one alphanumeric character.
 15. The display device as claimed inclaim 8, wherein the surface covered with the luminescent material islarger than the associated window.
 16. The display device as claimed inclaim 9, wherein the surface covered with the luminescent material islarger than the associated window.
 17. The display device as claimed inclaim 10, wherein the surface covered with the luminescent material islarger than the associated window.
 18. The display device as claimed inclaim 11, wherein the surface covered with the luminescent material islarger than the associated window.
 19. The display device as claimed inclaim 12, wherein the surface covered with the luminescent material islarger than the associated window.
 20. The display device as claimed inclaim 13, wherein the surface covered with the luminescent material islarger than the associated window.